1. Technical Field of the Invention
The present invention relates generally to above ground tanks that are used in the oil and gas industry to store fluids produced from underground hydrocarbon bearing formations, and more particularly to an improved method and an improved apparatus for containing spills or leaks from the above ground tanks so that such spills or leaks can be recovered or removed and disposed of properly before the environment is contaminated.
2. Description of the Related Art
During the production of oil or gas from an underground well, it is common for water to be produced along with the oil or gas. This water, called “produced water”, is typically separated from the oil or gas at the well site and temporarily stored in above ground storage tanks (ASTs). The produced water varies in quality from one well to the next, and it can have high quantities of minerals, salts, oil, gas, sand and other substances dissolved, mixed, or suspended in it. Produced water with a high concentration of impurities can be corrosive to the walls and ancillary piping of an AST and it can be toxic to the environment. A vehicle with a large storage tank attached to it periodically travels to the well site and transfers the produced water from the AST to the storage tank on the vehicle.
FIG. 1 illustrates an AST 100 with an input stream 18 and an outlet stream 20. The flow rate of the outlet stream 20 is manipulated by way of a valve 22. The produced water travels from the underground hydrocarbon bearing formation 6, up the oil or gas well bore hole 4, into a “Christmas Tree” 10, which is an assembly of valves, pipes and fittings used to control the flow of oil and gas from a well. The water separating section 14 of the Christmas Tree 10 directs the produced water to the AST 100. Other separating sections 12 direct the oil or gas into a pipeline 16, which transports the oil or gas to other locations for further processing or sale.
FIG. 2 illustrates the AST 100 of FIG. 1 after the produced water has created a hole 26 in the wall of the AST. The hole 26 allows the produced water to spill or leak out of the AST 100 and onto the ground 2.
In the United States, state and federal law restrict the discharge of produced water into the environment. With regards to ASTs, it is typically required that a secondary containment area be in place to collect any accidental discharge of produced water from an AST in the field. The secondary containment area usually needs to have the capacity and strength to hold at least 110% of the volume of the AST, or for an array of ASTs, 110% of the largest AST in the array. A need exists for an efficient, effective, and inexpensive method of building the secondary containment area for an AST.